JPS622812Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an oscillation device of a piezoelectric ultrasonic vibrator that emits sound waves to a liquid in a cleaning container using the bending vibration mode of a piezoelectric element bonded to the bottom surface of the cleaning container.

A conventional oscillation device of this type is shown in FIGS. 1 and 2. In Fig. 1, diodes 1 to 4 are for rectification, capacitor 5 is for DC smoothing or noise removal, and a rectified DC voltage is applied to both ends of capacitor 5, which is the DC power supply circuit. . A first transistor 6 and a second transistor 7 are connected in series together with protective resistors 8 and 9 between the positive side and the negative side of this DC power supply circuit. Bias resistors 10 and 11 are connected to each base, and a diode 2 for reverse voltage absorption is connected between each base and emitter.
6 and 27 are connected. Piezoelectric ultrasonic vibrator 1
7 is a chiyoke coil 16 and a feedback transformer 2
It constitutes a series circuit together with the primary winding 21 of 0, and is connected between the collector of the second transistor 7 and the negative side of the DC power supply circuit. Primary winding 2
A capacitor 18 is connected in parallel with the piezoelectric ultrasonic transducer 1, and a capacitor 19 is connected between the chiyoke coil 16 and the negative side of the DC power supply circuit to form a parallel resonant circuit and a series resonant circuit. We agree on points. A parallel circuit of a resistor 12 and a capacitor 14 and a parallel circuit of a resistor 13 and a capacitor 15 are connected to the bases of the first and second transistors 6 and 7, respectively, and a feedback transformer is connected between them and each emitter. Twenty secondary windings 23 and 22 are connected so that their winding directions are opposite.

Next, the operation of this oscillation device will be explained. Now, when the power is turned on, the first transistor 6
is turned on, and a current flows through the chiyoke coil 16, piezoelectric ultrasonic transducer 17, and primary winding 21, but it quickly saturates, and a back electromotive force is applied to the base of the first transistor 6, and conversely, the second A positive voltage is applied to the base of transistor 7,
They are turned off and on, respectively, and the energy stored in the chiyoke coil 16 and the piezoelectric ultrasonic transducer 17 flows through the second transistor 7. However, the second transistor 7 also saturates quickly, and a back electromotive voltage is induced in the base, turning it off.
Conversely, the first transistor 6 is turned on, and these steps are repeated to cause oscillation. That is, in this oscillation device, the current flowing through the piezoelectric ultrasonic vibrator 17 is converted into a voltage by the feedback transformer 20, and is fed back to the bases of the first and second transistors 6 and 7 in opposite phases to each other. The first and second transistors 6 and 7 are turned on and off alternately.

FIG. 2 shows an example of the piezoelectric ultrasonic transducer 17, in which a disk-shaped piezoelectric element 32 is connected to a cleaning container made of metal via an insulating plate 30 made of epoxy resin filled with glass cloth to which a copper foil 31 is attached. The piezoelectric element 32 and the copper foil 32 of the insulating plate 30
Lead wires 34 and 33 are soldered to a and 31, respectively, and serve as input terminals of this piezoelectric ultrasonic vibrator 17. When a high frequency voltage is applied to the piezoelectric ultrasonic vibrator 17 by this self-excited oscillator, ultrasonic waves are emitted to the liquid 29 in the cleaning container 28 due to bending vibration, and are used for ultrasonic cleaning etc. be able to.

However, the oscillation frequency of this device is mainly determined by the resonant frequency of the piezoelectric ultrasonic transducer 17, the parallel circuit of the primary winding 21 and the capacitor 18, the series circuit of the Chiyoke coil 16 and the capacitor 19, the Chiyoke coil 16 and the piezoelectric ultrasound The resonance point of the piezoelectric ultrasonic vibrator 17 is determined by a series circuit with the vibrator 17, a parallel circuit with the resistor 12 and the capacitor 14, and a parallel circuit with the resistor 13 and the capacitor 15. When using the piezoelectric ultrasonic transducer 1, there are a large number of resonant frequencies, and if the resonant frequencies of each circuit that determines the oscillation frequency are different from each other, the piezoelectric ultrasonic vibrator 1
When the resonance impedance of 7 changes, it moves to another resonance point, causing the oscillation frequency to change and become unstable.

Therefore, the purpose of this invention is to provide an oscillation device that has a small number of parts and can perform stable oscillation.

An embodiment of this invention is shown in FIG. That is, this oscillation device consists of the bases of the first and second transistors 6, 7 and the feedback transformer 20 in FIG.
In place of the parallel circuit of the resistor 12 and the capacitor 14 and the parallel circuit of the resistor 113 and the capacitor 15 connected between the secondary windings 23 and 22 of the , 7, and the cathodes thereof are connected to the secondary windings 23, 2 of the feedback transformer 20.
The capacitor 19 is omitted by using diodes 24 and 25 connected to the terminals 2 and 2, respectively.

The operation of this embodiment is similar to that of FIG. That is, the secondary winding 23 of the feedback transformer 20
Or, if the voltage generated at 22 is positive on the base side of the first or second transistor 6 or 7, the first
Or, it is considered that no voltage is applied to the base of the second transistor 6 or 7, but the junction capacitance or the emitter of the first or second diode 24 or 25 becomes negative, and the base becomes positive with respect to the emitter. , can sufficiently saturate the first or second transistor 6 or 7, and conversely, if the voltage generated in the secondary winding 23 or 22 is negative on the base side, the diode 2
4 or 25 is conductive, so the first or second
transistor 6 or 7 can be turned off.

In this way, the capacitor 14 connected to the bases of the first and second transistors 6, 7
By replacing the parallel circuit with the resistor 12 and the parallel circuit with the capacitor 15 and the resistor 13 with diodes 24 and 25, and omitting the capacitor 19, it is possible to reduce the factors that determine the oscillation frequency. It becomes easier to adjust the
Therefore, each oscillation frequency determining element, such as the choke coil 16 and the capacitor 18, can be set accurately so that the oscillation frequency does not deviate greatly, the oscillation frequency is stabilized, and the number of parts can be reduced, making it extremely useful industrially. be.

As described above, the oscillation device of this invention includes a DC power supply, a series circuit body of first and second transistors connected between the positive side end and the negative side end of the DC power supply, and the first and second transistors. a series circuit body of a chiyoke coil, a piezoelectric ultrasonic vibrator, and a capacitor connected between the connection point of the transistor No. 2 and the negative end of the DC power supply, and a feedback transformer with a primary winding connected in parallel to the capacitor; The first secondary winding of the feedback transformer is connected in series between the base and emitter of the first transistor so that the polarity is opposite to the base-emitter polarity of the first transistor. A diode 1 and a second secondary winding that generates a voltage with an opposite phase to the first secondary winding of the feedback transformer are interposed in series to change the polarity between the base and emitter of the second transistor. and a second diode connected between the base and emitter of the second transistor so that the polarity is opposite to that of the second transistor, the number of parts can be reduced and oscillation can be stabilized. be.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional oscillation device, FIG. 2 is a sectional view of a piezoelectric ultrasonic vibrator fixed to a cleaning container, and FIG. 3 is a circuit diagram of an embodiment of this invention. 1 to 4...Diode, 5...Capacitor,
6, 7...Transistor, 16...Chiyoke coil, 17...Piezoelectric ultrasonic transducer, 18...Capacitor, 20...Feedback transformer, 21...Primary winding, 22, 23...Secondary winding, 24, 25...Diode.

Claims (1)

[Scope of utility model registration request] A DC power supply, a series circuit of first and second transistors connected between the positive end and the negative end of the DC power supply, and a connection point between the first and second transistors and the negative end of the DC power supply. A series circuit body consisting of a chiyoke coil, a piezoelectric ultrasonic vibrator, and a capacitor connected between the side ends, a feedback transformer with a primary winding connected in parallel to this capacitor, and a first secondary winding of this feedback transformer. a first diode connected in series between the base and emitter of the first transistor such that the polarity is opposite to that between the base and emitter of the first transistor; and a first diode of the feedback transformer. A second secondary winding that generates a voltage with a phase opposite to that of the secondary winding is interposed in series so that the second secondary winding has a polarity opposite to that between the base and emitter of the second transistor. and a second diode connected between the base and emitter of the transistor.